This example makes the use of an LED Driver in order to control an almost endless amount of LEDs with only 4 Arduino pins. In this experiment, we use the CD4094 chip. Here, you can get the original version of this experiment: http://www.arduino.cc/en/Tutorial/LEDDriver . The Arduino team has used HEF4794.

An LED Driver has a shift register embedded that will take data in serial format and transfer it to parallel. It is possible to daisy chain this chip increasing the total amount of LEDs by 8 each time. You need to refer to datasheet for connecting more CD4094.

The code example you see here is taking a value stored in the variable dato and showing it as a decoded binary number. E.g. if dato is 1, only the first LED will light up; if dato is 255 all the LEDs will light up.

NOTE: Switch ON the IC1 -1 P DIP switch. If the switch is off, the 10pcs of LEDs connected to CD4094 will not work.